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SubjectRe: [PATCH -V6 10/14] hugetlbfs: Add memcg control files for hugetlbfs
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Andrew Morton <akpm@linux-foundation.org> writes:

> On Mon, 16 Apr 2012 16:14:47 +0530
> "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> wrote:
>
>> +#ifdef CONFIG_MEM_RES_CTLR_HUGETLB
>> +static char *mem_fmt(char *buf, unsigned long n)
>> +{
>> + if (n >= (1UL << 30))
>> + sprintf(buf, "%luGB", n >> 30);
>> + else if (n >= (1UL << 20))
>> + sprintf(buf, "%luMB", n >> 20);
>> + else
>> + sprintf(buf, "%luKB", n >> 10);
>> + return buf;
>> +}
>> +
>> +int __init mem_cgroup_hugetlb_file_init(int idx)
>> +{
>> + char buf[32];
>> + struct cftype *cft;
>> + struct hstate *h = &hstates[idx];
>> +
>> + /* format the size */
>> + mem_fmt(buf, huge_page_size(h));
>
> The sprintf() into a fixed-sized buffer is a bit ugly. I didn't check
> it for possible overflows because 32 looks like "enough". Actually too
> much.
>
> Oh well, it's hard to avoid. But using scnprintf() would prevent nasty
> accidents.
>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 519d370..0ccf934 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5269,14 +5269,14 @@ static void mem_cgroup_destroy(struct cgroup *cont)
}

#ifdef CONFIG_MEM_RES_CTLR_HUGETLB
-static char *mem_fmt(char *buf, unsigned long n)
+static char *mem_fmt(char *buf, int size, unsigned long hsize)
{
- if (n >= (1UL << 30))
- sprintf(buf, "%luGB", n >> 30);
- else if (n >= (1UL << 20))
- sprintf(buf, "%luMB", n >> 20);
+ if (hsize >= (1UL << 30))
+ scnprintf(buf, size, "%luGB", hsize >> 30);
+ else if (hsize >= (1UL << 20))
+ scnprintf(buf, size, "%luMB", hsize >> 20);
else
- sprintf(buf, "%luKB", n >> 10);
+ scnprintf(buf, size, "%luKB", hsize >> 10);
return buf;
}

@@ -5287,7 +5287,7 @@ int __init mem_cgroup_hugetlb_file_init(int idx)
struct hstate *h = &hstates[idx];

/* format the size */
- mem_fmt(buf, huge_page_size(h));
+ mem_fmt(buf, 32, huge_page_size(h));

/* Add the limit file */
cft = &h->mem_cgroup_files[0];



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